The multi-type air conditioner, the heat pump hot-water supplying apparatus or the refrigerating apparatus incorporates a heat exchange unit. The heat exchange unit is generally called a “heat source unit,” and will hereinafter be referred to as a “heat source unit.”
The heat source unit comprises a heat exchanging chamber, a machine compartment, air, heat exchangers arranged in the heat exchanging chamber, blowers configured to supply air to the air heat exchangers, and refrigeration cycle components provided in the machine compartment. Two air heat exchangers are provided in one unit. The air heat exchangers are arranged to face each other and form a unit shaped like a V. This is one of the characterizing features of the heat source unit.
The machine compartment is shaped like an inverted V. This is one of the characterizing features of the machine compartment. The refrigeration cycle parts that the machine compartment incorporates are a compressor, a four-way valve, the above-mentioned heat exchangers, an expansion valve, and a water heat exchanger. A plurality of heat source units of this type are arranged side by side, constituting one apparatus.
In any heat source unit of this type, a plurality of compressors are arranged parallel in most cases, constituting one refrigeration cycle.
At the bottom of the compressor, an oil reservoir is provided to collect lubricating oil. As the shaft rotates, the oil is drawn up by suction from the oil reservoir and applied to the sliding part of the compressor mechanical, section. Most of the lubricating oil so applied flows back to the oil reservoir. Only a part of the oil is mixed with the refrigerant gas and ejected into the refrigeration cycle, and returns to the oil reservoir after circulating in the refrigeration cycle.
If a plurality of compressors are connected in parallel in one refrigeration cycle as has hitherto been practiced, a subtle, pressure difference will be observed between the compressors. This difference causes the lubricating oil to flow into the compressor at the lowest pressure. If this state is prominent, the lubricating oil will accumulate in one compressor, and will scarcely exists in any other compressor. Consequently, the compressor mechanism section may suffer from a burnout in some cases.
Therefore, the compressors arranged in parallel are connected by oil balancing pipes, constituting an additional circuit, and a resisting member is provided in the refrigerant intake pipe of each compressor, inducing a forced pressure loss. This measure holds the lubricating oil at the same level in the compressors, preventing the oil from accumulating in one compressor only.
If a forced pressure loss is induced in any compressor, however, the compressor will have its compressing, ability decreased. The compressor should therefore be replaced by a compressor having a compressing ability one rank higher. Further, a system must be used to confirm whether the oil is reliably applied in the compressor. This inevitably influence the cost.
In winter, water may be frozen, forming frost on the air heat exchangers, while the air heat exchangers are operating in the heating mode. In this case, the air heat exchangers must be driven in defrosting mode. More specifically, the heating cycle is switched to the cooling cycle, in which the refrigerant is condensed in the air heat exchangers, melting the frost with the resulting heat of condensation. At this point, however, if any compressor has a trouble, the other compressors cannot be drive to achieve defrosting.